Don't call it a comeback. Not because Mariah Carey's ''Charmbracelet'' sold some 241,000 copies this week, according to SoundScan, one of the strongest debuts of her career. Rather, because Carey was unable to unseat the still-indomitable Shania Twain, whose ''Up!'' has held the No. 1 spot on the Billboard chart for three weeks of now, moving another 317,000 units this week. Carey had to settle for third place, as she also couldn't dislodge Tim McGraw's ''Tim McGraw & the Dancehall Doctors,'' which held at No. 2 for its second week of release and sold another 250,000 discs.
Holding at No. 4 was ''NOW That's What I Call Music! Vol. 11,'' on sales of 222,000. The ''8 Mile'' soundtrack slipped two slots to No. 5, selling another 220,000 copies. Rounding out the top 10 were Avril Lavigne's ''Let Go,'' up three notches to No. 6; Jennifer Lopez's ''This Is Me...Then,'' sliding one slot to No. 7; Tupac's ''Better Dayz,'' dropping three places to No. 8; the Dixie Chicks' ''Home,'' rising eight spots to No. 9; and Faith Hill's ''Cry,'' down three to No. 10.